{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,1,19]],"date-time":"2026-01-19T06:01:20Z","timestamp":1768802480865,"version":"3.49.0"},"reference-count":49,"publisher":"MDPI AG","issue":"4","license":[{"start":{"date-parts":[[2018,3,22]],"date-time":"2018-03-22T00:00:00Z","timestamp":1521676800000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"National Fund for Scientific and Technological Development of Chile - FONDECYT","award":["11130463"],"award-info":[{"award-number":["11130463"]}]},{"name":"National Fund for Scientific and Technological Development of Chile - FONDECYT","award":["1151299"],"award-info":[{"award-number":["1151299"]}]},{"name":"IMO-Chile"},{"name":"Coastal and Marine Research Institute (INVEMAR) and the Administrative Department of Science, Technology and Innovation (COLCIENCIAS) of Colombia","award":["COLCIENCIAS-INVEMAR FP44842-499-2014"],"award-info":[{"award-number":["COLCIENCIAS-INVEMAR FP44842-499-2014"]}]},{"name":"Fondo Nacional de Financiamiento para la Ciencia, la Tecnolog\u00eda y la Innovaci\u00f3n Francisco Jos\u00e9 de Caldas"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Remote Sensing"],"abstract":"<jats:p>An approach that improves the spectral-based PHYSAT method for identifying phytoplankton functional types (PFT) in satellite ocean-color imagery is developed and applied to one study case. This new approach, called PHYSTWO, relies on the assumption that the dominant effect of chlorophyll-a (Chl-a) in the normalized water-leaving radiance (nLw) spectrum can be effectively isolated from the signal of accessory pigment biomarkers of different PFT by using Empirical Orthogonal Function (EOF) decomposition. PHYSTWO operates in the dimensionless plane composed by the first two EOF modes generated through the decomposition of a space\u2013nLw matrix at seven wavelengths (412, 443, 469, 488, 531, 547, and 555 nm). PFT determination is performed using orthogonal models derived from the acceptable ranges of anomalies proposed by PHYSAT but adjusted with the available regional and global data. In applying PHYSTWO to study phytoplankton community structures in the coastal upwelling system off central Chile, we find that this method increases the accuracy of PFT identification, extends the application of this tool to waters with high Chl-a concentration, and significantly decreases (~60%) the undetermined retrievals when compared with PHYSAT. The improved accuracy of PHYSTWO and its applicability for the identification of new PFT are discussed.<\/jats:p>","DOI":"10.3390\/rs10040498","type":"journal-article","created":{"date-parts":[[2018,3,22]],"date-time":"2018-03-22T05:14:55Z","timestamp":1521695695000},"page":"498","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":9,"title":["Improving the Remote Sensing Retrieval of Phytoplankton Functional Types (PFT) Using Empirical Orthogonal Functions: A Case Study in a Coastal Upwelling Region"],"prefix":"10.3390","volume":"10","author":[{"given":"Marco","family":"Correa-Ramirez","sequence":"first","affiliation":[{"name":"Programa de Geociencias, Instituto de Investigaciones Marinas y Costeras INVEMAR, Santa Marta 470006, Colombia"},{"name":"Escuela de Ciencias del Mar, Pontificia Universidad Cat\u00f3lica de Valparaiso, Valparaiso 2340000, Chile"}]},{"given":"Carmen","family":"Morales","sequence":"additional","affiliation":[{"name":"Departamento de Oceanograf\u00eda, Facultad de Ciencias Naturales y Oceanogr\u00e1ficas, Universidad de Concepci\u00f3n, Concepci\u00f3n 4070386, Chile"},{"name":"Instituto Milenio de Oceanograf\u00eda (IMO-Chile), Concepci\u00f3n 4030000, Chile"}]},{"given":"Ricardo","family":"Letelier","sequence":"additional","affiliation":[{"name":"College of Earth, Ocean, and Atmospheric Sciences, Oregon State University, Corvallis, OR 97331, USA"}]},{"given":"Valeria","family":"Anabal\u00f3n","sequence":"additional","affiliation":[{"name":"Instituto Milenio de Oceanograf\u00eda (IMO-Chile), Concepci\u00f3n 4030000, Chile"},{"name":"Instituto de Oceanograf\u00eda y Cambio Global, Universidad de Las Palmas de Gran Canaria, Campus Universitario de Tafira, 35017 Las Palmas de Gran Canaria, Spain"}]},{"given":"Samuel","family":"Hormazabal","sequence":"additional","affiliation":[{"name":"Escuela de Ciencias del Mar, Pontificia Universidad Cat\u00f3lica de Valparaiso, Valparaiso 2340000, Chile"},{"name":"Instituto Milenio de Oceanograf\u00eda (IMO-Chile), Concepci\u00f3n 4030000, Chile"}]}],"member":"1968","published-online":{"date-parts":[[2018,3,22]]},"reference":[{"key":"ref_1","unstructured":"Sathyendranath, S. 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